1. Field of the Invention
This invention relates to a resonator that works in conjunction with an active noise cancellation module to reduce low frequency engine noises.
2. Related Art
Internal combustion engines include air induction systems for conducting air to engine cylinders. Engine noise is propagated through the air induction systems, which is undesirable. Noise attenuation mechanisms have been installed within the air induction systems to reduce these noises. For this application, this noise attenuation mechanism is referred to as an Active Noise Cancellation (ANC) system and includes a speaker, a microphone, and a signal generator that are mounted within an air inlet duct housing. The microphone detects the noise and generates a noise signal that is sent to the signal generator. The signal generator phase-shifts the signal and sends the signal to the speaker to generate a sound field that cancels out the noise that is being detected by the microphone.
High power requirements and large speaker sizes are required to reduce engine noise levels below accepted values. Typically, engine noise must be reduced below 110 Hertz (Hz). This causes the ANC system to be very large, taking up a considerable amount of packaging space. Additionally, these ANC systems draw a large amount of power from the vehicle electrical system in order to effectively cancel the high levels of low frequency noise.
It is the object of the present invention to provide an ANC system that overcomes the deficiencies outlined above.